421. Maximum XOR of Two Numbers in an Array
Given an integer array nums, return the maximum result of nums[i] XOR nums[j], where 0 <= i <= j < n.
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| struct Trie {
Trie* next[2];
Trie() {
memset(next, 0, sizeof(next));
}
};
class Solution {
Trie* trie;
public:
int findMaximumXOR(vector<int>& nums) {
trie = new Trie();
int res = 0;
for(auto n : nums) insert(n);
for(auto n : nums) res = max(res, search(n));
return res;
}
void insert(int n) {
Trie* node = trie;
for(int i = 31; i >= 0; i--) {
int bit = (n>>i) & 1;
if(!node->next[bit]) node->next[bit] = new Trie();
node = node->next[bit];
}
}
int search(int n) {
Trie* node = trie;
int res = 0;
for(int i = 31; i >= 0; i--) {
int bit = (n>>i) & 1;
if(node->next[!bit]) {
res += (1<<i);
node = node->next[!bit];
} else node = node->next[bit];
}
return res;
}
};
|
